This invention is concerned with a throw-away or disposable ink cartridge particularly useful in code dating machines.
Code dating machines are marking devices which print certain indicia in ink on labels and packages for foods and other goods. Such machines generally include a frame assembly to which is mounted a reciprocating positioning mechanism for a printing head having raised indicia thereon, usually made of rubber and adapted to be displaced between an ink receiving position and a marking position. In the marking position, the printing head engages the substrate to be printed. To achieve the ink receiving position, the printing head is intermittently displaced from its marking position to an ink storage device or cartridge also mounted on the frame. The printing head engages the ink storage device to receive a supply of ink therefrom and then is returned by the positioning mechanism to the marking position where the substrate is printed. The process continues in reciprocating fashion until the ink supply in the ink storage device is expended.
Prior ink storage devices or cartridges employed with such marking devices have to be refilled with an ink supply after they are expended through use. This is often a tedious and messy operation causing the user to contaminate his hands and clothes with ink and expending valuable time. If the user decides to fill many cartridges at once and use one while storing the others the solvent vehicle for the ink evaporates from the cartridge due to the inadequate sealing means covering the cartridge. More recently cartridges have been developed which are disposable, non-refillable and have long shelf lives hence avoiding the above problems. Many disposable cartridges employ a layer of felt or the like mounted atop an absorbent sponge material in the cartridge wherein the felt layer engages the printing head in the ink receiving position. Oftentimes flooding occurs in these cartridges which arises from changes in temperature. When a cartridge containing a felt overlayer is exposed to low temperatures the felt and sponge contract and the ink becomes quiessent. Consequently the felt layer does not become ink saturated. However, when the temperature rises to room temperature or above the sponge and felt expand and the ink becomes active or non-quiessent and is caused to flow to the felt surface and flood the top of the cartridge. As a result the user must decant the excess ink from the cartridge or blot it out of the cartridge prior to use. This materially reduces the usuable life of the cartridge.
The present invention provides a disposable ink cartridge for marking devices comprising a sponge overlaid by a felt layer which can be used until its ink supply is expended and then disposed of and which contains a means for preventing the flooding of the cartridges as a result of temperature differences. In another embodiment of the invention, means associated with the felt layer are provided to filter undissolved materials from the ink supply into the cartridge.